It has become apparent within recent years that the finite limit to the availability of fluid fossel energy sources indigenous to the earth such as oil and natural gas is being approached. This situation coupled with the increased demand for energy makes it imperative that new sources and their respective conversion to useful forms, i.e. power generation, be found and developed. In view of this situation it seems logical that the remaining types of fossel fuels should be conserved and perhaps utilized only with respect to motive power requirements such as transportation needs. If other energy sources such as geothermal and solar energy are employed for generating electric power, then over 53 percent of our power requirements could be satisfied with an inexhaustible supply of energy. This fact becomes very important when consideration is given to the energy content of available fossel fuels. The fossel fuel contains approximately 16,000 BTU per pound thus making them well suited for the mobile type of applications. On the other hand the amount of useful solar energy that is necessary for supplying any relatively large power need requires large areas for collection, since the intensity of solar energy being radiated to the earth is not large. Thus, from pragmatic considerations solar energy systems would have to be relegated to a stationary type of power generation application. The same situation exists with respect to geothermal energy sources.
The most abundant type of geothermal source consists of hot water supplies which have a relatively low energy content of about 300 BTU/lb. at 400.degree. F when compared to fossel fuels on a weight basis. Because of this fact, this energy source can also only be effectively utilized in a stationary type of power generation application. Due to the low energy content with respect to the heating of liquids by solar radiation or the use of geothermal sources it is necessary to employ very large flow rates of these hot liquid sources in order to obtain the magnitude of power required. The necessity of large flow rates indirectly implies that relatively large equipment sizes would be required and with the specific application of power generation the system would be required to operate for extended periods of time. Inherent in this application are the substantial problems concerning the contamination of the equipment used, mainly the primary heat exchangers, since the fluid energy sources in many cases is saturated with solutes and they tend to precipitate out as solid matter when the equilibrium thermodynamics of these fluids are disturbed by the power extraction process. Therefore, in order for the power extraction from these hot fluid energy sources to be viable a very economical process has to be employed wherein the capital cost and operating cost have to be reasonable with respect to the power output. Thus, the system must not be susceptible to any contamination related to the precipitation of solutes contained in the energy providing sources; must be reasonable with respect to capital and maintenance cost as related to the given power output and effective length of time required to operate; and also must not create any environmental hazards such as pollution.